Calibrating developer & film

<p>Hi All,</p>

<p>I use Ilfotec HC developer, mostly because I have a 1 litre bottle of it and it is the same price as 2 1l bags of D76 out here. Given the 1:29 dilution that makes it very economical.</p>

<p>However, while everything out there lists times for D76 not everything lists times for Ilfotec HC.<br>

It has always worked a treat on Ilford film.</p>

<p>However, I just got a good deal on the following films and bought some:<br>

Rollei Retro 100 35mm (OK, I can use times for Agfa here)<br>

Rollei Retro 400S 120 (13.5 minutes was suggested to me)<br>

Foma 400 35mm - no idea here. According to the Foma data sheet it is really only ASA 250 - but this is fine. Exposing at 250 and using Foma's recommended times in D76 is worked very well indeed:<br>

<p>Is there an easy way of calibrating all of this in a scientific way without densitometers or the like?<br>

I also have Rollei Infrared. Is there any reason why I should not also use Ilfotec HC on this too?</p>

<p>I did inherit a Paterson darkroom exposure gadget in a box of someone else's ex darkroom stuff but I have no idea how to use it. Would it help?</p>

<p>Also, how would I got about experimenting with different dilutions? People seem to use Ilfotec LC29 as varying dilutions not in accordance with Ilford recommendations.</p>

<p>Cheers,</p>

<p>--Irvine</p>

 

<p>Hi Irvine,<br>

"Is there an easy way of calibrating all of this in a scientific way without densitometers"<br>

I don't think so. That's what densitometers are about, calibrating in an easy and scientific way. Having said that, you could probably improvise by comparing negatives to older ones that have your preferred contrast and density. However, I have tried this in the past and found it frustrating. The densitometer way is the easiest by far (quick and accurate), as I found out after I bought a timer that incorporates being a transmission densitometer (therefore more affordable). It was definitely one of the best buys I made for my darkroom....<br>

As to your question on experimenting with dilutions (and then obviously with developing times as well): I'm curious if someone will come up with a brilliant idea, but I have found differences impossible to judge without a densitometer, unless the results were totally off. With a meter you can produce a curve from a testseries and adjust according to what you aiming for. Without measurements your out in the woods without a compass.<br>

I'm sorry for not giving an answer more in line with what you looking for, good luck, Bert</p>

<p> </p>

<p>Hi Bert,</p>

<p>Thanks for the info. I had an idea that densitometers were not all that cheap or readily available - which has just been born out by a complete absence of them on our South African auction and classified ad web sites.</p>

<p>On Ebay they seems to be in the order of hundreds of dollars at least, so it would seem I am looking at best for "guided trial and error."</p>

<p>Has anyone done this?</p>

<p>What about shooting a whole roll of the same scene with a range of tones and at the desired ASA and then cutting it into strips of 3 of 4 frames and developing at various times until it seemed "about right?"</p>

<p>Cheers,</p>

<p>--Irvine</p>

<p> </p>

<p>Many of us do not use densitometers. That doesn't mean we are not scientific in calibrating the process. You can use your preferred normal contrast grade paper to calibrate.</p>

<p>First, develop an unexposed negative (or leave a frame or two blank). Use them to establish "proper proofing time" by contact printing a test strip on grade 2 paper. The proper proofing time, for a given light source and height (and f/stop if you are using an enlarger) is the minimum time that gives you a maximum black on the paper (i.e., the first strip that shows max black under a normal light source. Don't evaluate under very bright light or sunlight, as you will see too many gradations).</p>

<p>Once you have that time and set-up, do a film speed test to determine your personal E.I. Meter an evenly-lit subject like a gray card or wall and underexpose 4 stops (placing it on Zone I if you are a Zone System user). Bracket around this two stops in either direction in 1/3-stop increments. Develop at your best guess at a deveopment time (it doesn't matter too much what time at this point). Contact print these negatives at your proper proofing time on the same paper (with enlarger/light source height and f/stop all the same). The negative that shows the first shade of black slightly lighter than max black is the one exposed at the proper film speed (figure that out from how much you under or overexposed from box speed). This is now your EI for that film and paper.</p>

<p>Now, using that film speed, go back to your evenly-lit wall or whatever. This time you want to make three identical negatives at three stops over the meter reading. Develop these at an estimated starting time, 20% more time, 20% less time. Contact print these negatives at your proper proofing time. The negative that gives a shade of gray slightly lighter than maximum white (i.e., minimum paper density) is the correct developing time. If you don't get exactly the tone of light gray you want, either extrapolate or test again using the first test's closest development time as a starting point.</p>

<p>When you finish with this process, you have the right E.I. and developing time for that film/paper for normal contrast scenes. If you wish to use the Zone System, you can repeat the above for expansions and contractions. If you are a roll-film user, I would recommend you handle contrast adjustments with paper grade. The only adjustment you need to make in exposure and development is to be sure to overexpose one stop for contrastier than normal situations if you are using an in-camera averaging meter (yes, overexpose).</p>

<p>That's it in a nutshell, rather oversimplified. If you feel like this method will work for you, there is a lot of info here and on other forums dedicated to photography. Just search.</p>

<p>Best and good luck,</p>

<p>Doremus Scudder</p>

<p>Hi Doremus,</p><p><br></p><p>Thanks for taking the time to explain all that!</p><p>I have a few questions but I need to digest it all first.</p><p>--Irvine</p><p><br></p><p><br></p><p><br></p>

<p>There is an excellent description of film/processing calibration, without a densitometer, in the Kodak book "Advanced Black and White Photogrraphy," which I believe you can still get at Amazon.<br>

The process uses a step wedge for comparison. <br>

Worked for me.</p>

<p>Like Dormus, I determine film speed and development by reference to the final print. I'd also suggest you look at Adams' 'The Negative'.</p>

<p>Hi,<br>

Thanks to all for your advice, it seems I have a lot to learn about an area of photography I had not yet considered.<br>

I have been having deep thoughts about all of this. My initial problem is that it is going to be another few months before my darkroom is completed. Right I can only process and scan - and then only 120 as my flatbed is not really good enough for 35mm.</p>

<p>Cheers,</p>

<p>--Irvine</p>

 

<p>John Blakemore's excellent book "Black & White Photography Workshop" shows how to do these tests without any need for densitometers.</p>

<p >Now the object of "straight" photography is to reproduce objects on film and paper with fidelity. To accomplish we need to calibrate all materials and processes. It all started with Ferdinand Hurter (Swiss 1844-1998 and V.C Driffield (England 1848-1915). These men made the first light meter and the first graphs (Plots) of films and papers as to how they responded to exposure and developing. Today, such plots are called H&D curve in their honor. They published in 1890.</p>

<p >Today we use a Sensitometer to accurately expose and a densitometer to accurately read and draw graphs (plots). Generally the sensitometer is set to expose film in 1/2 f/stop increments. The resulting film has 21 steps from D-min to D-Dax and is called a step wedge because in the early day's film was exposed thru a wedge of glass that resembled a miniature staircase with 21 steps. </p>

<p >Consider that if you photograph an object and its image on the film closely resembles the original, you have a winner. Even better if a print or slide made from the film yields an image that closely resembles the original you truly have success. Now only one shade or tone meets this target. A placard battleship gray with a surface that reflects 18% of the light incent upon it. If photographed with correct exposure, the resulting film image of this card transmits 18%. Additionally, a positive print, an image of the gray card, made from this film reflects 18% of the light incident upon it. In other words, a gray card reproduces on film approximately the same as the original and a print made from this film yields an image that approximates the original card. Thus, the 18% gray card is an important calibration tool for all manor or photo instrumentation. </p>

<p >What I am trying to say is, there is no simple calibration method but you can run meaningful tests using a gray card. You can make a print of your image of the gray card and lay it on top of the original card. You can visually see differences. You can purchase step films paper gray scales and use these as calibration targets. You can use your light meter or an enlarging meter, they can function as crude but effective densitometers. </p>

<p >Some facts and numbers you might find useful. </p>

<p >The densitometer reads out in density (units). We shine a light of known intensity through film and onto paper. For films, we measure the amount of light that transverses (transmission) or the amount of light reflected (reflection). We assign a numerical value. </p>

<p >T (transmission) = amount that gets through ÷ light that plays on the film.</p>

<p >O (opacity) = amount that hits ÷ amount that get through. </p>

<p >D (density) O expressed as a log base 10 (base is omitted and only the exponent is written).</p>

<p > </p>

<p >Suppose 100 units of light hits the film in a specific area. If only 50 units emerges, then T = 50% (we express T as a percentage). Now the inverse of 50% or as is the convention , we write it in decimal notion thus 2.0. We call this value Opacity. Once the opacity is known, the convention is to write this value using logarithmic notation base 10. Thus opacity 2 = 10 elevated to the 0.30 power. We write this as 0.30. Thus, an area of film that transmits 50% has an opacity of 2.0 and a density of 0.30.</p>

<p >Some values:</p>

<p >Density = .1 Opacity = 1.26 T = 79% (1/3 f/stop)</p>

<p >Density = .20 Opacity = 1.59 T = 63% (2/3 f/stop)</p>

<p >Density = .30 Opacity = 2.0 T = 50% (1 f/stop)</p>

<p >Density = .60 Opacity = 3.98 T = 25% (1 1/3 f/stop)</p>

<p >Density = .90 Opacity = 7.94 T = 12.5% (1 1/2 f/stop)</p>

<p >Density = 1.2 Opacity = 15.85 T = 6.3% ( 2/3 f/stop)</p>

<p >Density = 1.5 Opacity = 31.6 T = 3.3% (2/3 f/stop)</p>

<p > </p>

<p >The gray card is measured via a reflection densitometer. This instrument beams light of a known intensity at the reflective copy. We measure the intensity of the rebound (reflected) light. </p>

<p >The gray card measures Reflected Density .75. Its Absorbance is 5.55 it reflects 18%</p>

<p>Correction:</p>

<p >Density = 1.2 Opacity = 15.85 T = 6.3% (4 f /stop)</p>

<p >Density = 1.5 Opacity = 31.6 T = 3.3% (5 f/stop)</p>

 

<p>Hi All,</p>

<p>Thanks again for all the advice and insight.</p>

<p>It seems I am going to have to leave this for the future when my darkroom is up and runnning and I have more experience to build on. I can see the skills and techniques learned in the process will be very useful.</p>

<p>In the mean time it seems Google is my friend.</p>

<p>There are quite a few examples of folks using Ilfotec out there, I will just have to use those as a starting point for now.</p>

<p>Cheers,</p>

<p>--Irvine</p>

<p> </p>

<p>I am still a big fan of Fred Picker's Zone VI Studios video on "Photographic Techniques." It's the best presentation I have seen for testing different films and developers. It's available used on Ebay or from Calumet Photo who re-released them on DVD. Have fun! Randy</p>